In fabrication of semiconductor devices, a CMP (chemical mechanical planarization) process is used in planarization of an insulating layer or metal layer on a wafer surface or wafer. For example, a Cu layer is deposited to a thickness of 30,000 Å or more in a through-silicon via (TSV) process during fabrication of semiconductor devices. A CMP slurry composition is used in polishing such a Cu layer. In a process in which such a CMP slurry composition is used to polish the Cu layer, it is necessary to secure an appropriate planarization degree along with a sufficient polishing rate. Otherwise, a polishing time becomes longer or surface defects such as erosion and dishing can occur.
In the CMP process, a polishing pad is placed on a polishing platen, followed by application of hydrostatic pressure while a polishing head holds and rotates a wafer during rotation of the polishing platen. As a result, the CMP process can planarize a wafer surface layer through polishing using mechanical polishing action by the polishing pad and a polishing agent of a polishing slurry composition and chemical polishing action by an oxidant of the polishing slurry composition. Generally, a polishing slurry composition used in CMP may include: a polishing agent of metal oxide particles; deionized (DI) water in which the polishing agent is suspended; an oxidant removing a metal oxide by forming a passivation layer on a surface of a metal film; a corrosion inhibitor preventing excessive corrosion by passivation; and a complexing agent chelating the metal oxide oxidized by the oxidant.
Recently, there has been proposed a method in which organic particles are used instead of a polishing agent of metal oxide particles. However, typical organic particles exhibit poorer physical properties than metal oxide particles and thus have lower polishing rate. Particularly, typical organic particles have a negative (−) surface charge, and a Cu layer is oxidized into CuO or Cu2O during polishing and thus also has a negative (−) surface charge. As a result, a repulsive force is created between the organic particles and the Cu layer, causing reduction in polishing amount.
Therefore, there is a need for a CMP slurry composition which has better polishing properties than typical organic particles while exhibiting excellent polishing rate.